// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/net/view_http_cache_job_factory.h"

#include <stddef.h>

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/location.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/numerics/safe_conversions.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/string_util.h"
#include "base/threading/thread_task_runner_handle.h"
#include "content/public/common/url_constants.h"
#include "net/base/completion_callback.h"
#include "net/base/net_errors.h"
#include "net/url_request/url_request.h"
#include "net/url_request/url_request_simple_job.h"
#include "net/url_request/view_cache_helper.h"

namespace content {
namespace {

    // A job subclass that dumps an HTTP cache entry.
    class ViewHttpCacheJob : public net::URLRequestJob {
    public:
        ViewHttpCacheJob(net::URLRequest* request,
            net::NetworkDelegate* network_delegate)
            : net::URLRequestJob(request, network_delegate)
            , core_(new Core)
            , callback_(base::Bind(&ViewHttpCacheJob::OnStartCompleted,
                  base::Unretained(this)))
            , weak_factory_(this)
        {
        }

        // net::URLRequestJob implementation.
        void Start() override;
        void Kill() override;
        bool GetMimeType(std::string* mime_type) const override
        {
            return core_->GetMimeType(mime_type);
        }
        bool GetCharset(std::string* charset) override
        {
            return core_->GetCharset(charset);
        }
        int ReadRawData(net::IOBuffer* buf, int buf_size) override
        {
            return core_->ReadRawData(buf, buf_size);
        }

    private:
        class Core : public base::RefCounted<Core> {
        public:
            Core()
                : data_offset_(0)
                , callback_(base::Bind(&Core::OnIOComplete, this))
            {
            }

            int Start(const net::URLRequest& request, const base::Closure& callback);

            // Prevents it from invoking its callback. It will self-delete.
            void Orphan()
            {
                user_callback_.Reset();
            }

            bool GetMimeType(std::string* mime_type) const;
            bool GetCharset(std::string* charset);
            int ReadRawData(net::IOBuffer* buf, int buf_size);

        private:
            friend class base::RefCounted<Core>;

            ~Core() { }

            // Called when ViewCacheHelper completes the operation.
            void OnIOComplete(int result);

            std::string data_;
            size_t data_offset_;
            net::ViewCacheHelper cache_helper_;
            net::CompletionCallback callback_;
            base::Closure user_callback_;

            DISALLOW_COPY_AND_ASSIGN(Core);
        };

        ~ViewHttpCacheJob() override { }

        void StartAsync();
        void OnStartCompleted();

        scoped_refptr<Core> core_;
        base::Closure callback_;

        base::WeakPtrFactory<ViewHttpCacheJob> weak_factory_;

        DISALLOW_COPY_AND_ASSIGN(ViewHttpCacheJob);
    };

    void ViewHttpCacheJob::Start()
    {
        base::ThreadTaskRunnerHandle::Get()->PostTask(
            FROM_HERE,
            base::Bind(&ViewHttpCacheJob::StartAsync, weak_factory_.GetWeakPtr()));
    }

    void ViewHttpCacheJob::Kill()
    {
        weak_factory_.InvalidateWeakPtrs();
        if (core_.get()) {
            core_->Orphan();
            core_ = NULL;
        }
        net::URLRequestJob::Kill();
    }

    void ViewHttpCacheJob::StartAsync()
    {
        DCHECK(request());

        if (!request())
            return;

        int rv = core_->Start(*request(), callback_);
        if (rv != net::ERR_IO_PENDING) {
            DCHECK_EQ(net::OK, rv);
            OnStartCompleted();
        }
    }

    void ViewHttpCacheJob::OnStartCompleted()
    {
        NotifyHeadersComplete();
    }

    int ViewHttpCacheJob::Core::Start(const net::URLRequest& request,
        const base::Closure& callback)
    {
        DCHECK(!callback.is_null());
        DCHECK(user_callback_.is_null());

        AddRef(); // Released on OnIOComplete().
        std::string cache_key = request.url().spec().substr(strlen(kChromeUINetworkViewCacheURL));

        int rv;
        if (cache_key.empty()) {
            rv = cache_helper_.GetContentsHTML(request.context(),
                kChromeUINetworkViewCacheURL,
                &data_, callback_);
        } else {
            rv = cache_helper_.GetEntryInfoHTML(cache_key, request.context(),
                &data_, callback_);
        }

        if (rv == net::ERR_IO_PENDING)
            user_callback_ = callback;

        return rv;
    }

    bool ViewHttpCacheJob::Core::GetMimeType(std::string* mime_type) const
    {
        mime_type->assign("text/html");
        return true;
    }

    bool ViewHttpCacheJob::Core::GetCharset(std::string* charset)
    {
        charset->assign("UTF-8");
        return true;
    }

    int ViewHttpCacheJob::Core::ReadRawData(net::IOBuffer* buf, int buf_size)
    {
        DCHECK_LE(data_offset_, data_.size());
        int remaining = base::checked_cast<int>(data_.size() - data_offset_);
        if (buf_size > remaining)
            buf_size = remaining;
        memcpy(buf->data(), data_.data() + data_offset_, buf_size);
        data_offset_ += buf_size;
        return buf_size;
    }

    void ViewHttpCacheJob::Core::OnIOComplete(int result)
    {
        DCHECK_EQ(net::OK, result);

        if (!user_callback_.is_null())
            user_callback_.Run();

        // We may be holding the last reference to this job. Do not access |this|
        // after Release().
        Release(); // Acquired on Start().
    }

} // namespace.

// Static.
bool ViewHttpCacheJobFactory::IsSupportedURL(const GURL& url)
{
    return url.SchemeIs(kChromeUIScheme) && url.host_piece() == kChromeUINetworkViewCacheHost;
}

// Static.
net::URLRequestJob* ViewHttpCacheJobFactory::CreateJobForRequest(
    net::URLRequest* request, net::NetworkDelegate* network_delegate)
{
    return new ViewHttpCacheJob(request, network_delegate);
}

} // namespace content
